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Details of Some Components Used for Subsidiary Services in Aircraft Ground Power Unit Auto Diesels Ltd. are now manufacturing for the N.A.T.O. Air Forces a ground starter using a Rolls- Royce industrial reciprocating engine. The Rolls-Royce B.60 engine operating at constant speed and closely governed at 3,000 r.p.m. developing 86 b.h.p. at a continuous rating of 131 deg. F. is flexibly coupled to a special Crompton Parkinson d.c. generator with a direct-coupled exciter. The con tinuous output is 22 kW. at 28·5 volts (770 amps.) with an intermittent rating of 185 per cent full load current (1,425 amps.) for one minute. Servicing and starting loads are possible at constant voltage supply which is achieved by a special design generator. Alternatively, constant current or current limitation control can be selected to cater for the wide range of aircraft with which the unit will be used. and the coincidence of the star and the sextant bubble available sealed or unsealed: the sealed version can Current limitations can be effected at selected is maintained by manipulating the altitude control. withstand pressure differences of up to 30 Ib/sq. in. values of 800, 1,000, 1 200 and 1,400 amps. When This starts an electric motor which adjusts the posi and can have either male or female contact; operated under constant voltage control the voltage is tion of a prism at the top of the sextant tube. held constant at the end of the supply cables and at bulkhead mounted connectors for fitting to A star is simulated by the light from a bulb directed the aircraft terminals regardless of load current pressure bulkheads through which cables have through a collimator set horizontally and on to a variations. Three separate supply cables are incor to pass, but where quick connexion and dis 45 deg. mirror. The collimator makes the source of porated to cater for all types of aircraft in service. connexion are required on each side of the bulk light appear to be at infinity. From the 45 deg. mirror Separate service and starting outputs are available as head. These connectors are sealed axially by a the light is reflected on to a second mirror which can required. Normal overload, over voltage and reverse glass seal and incorporate an annular sealing ring be tilted and revolved through 360 deg. round the nose current protection is provided. between the flange and the bulkhead. They will of the sextant. The whole equipment is mounted on a trolley and withstand a pressure difference of up to 301b/sq. in. The new simulator is suitable for stars at an alti is weatherproofed. Pre-production models were sub Connectors are silver plated and will operate tude of from 15 deg. to 39 deg. and is accurate to ± ject to extensive endurance and environmental tests satisfactorily at temperatures of up to 250 deg. C. The 1 min. The azimuth setting is within ± ½ deg. including cold and hot start operation, rain, salt PTFE insulator is shaped to provide a long narrow water and humidity tests. leakage path. Practical frequency limit is 10,000 Mc/s. Jet Engine Analyser The voltage/standing wave ratio is less than 1 ·35:1 in a 50 ohm system. Maximum voltage is 500 volts; Star Simulator Testing of a turbojet engine on the bench or in an current carrying capacity is one ampere. All connectors aircraft, without running the engine or disconnecting For training navigators on the ground in the use of are interchangeable with their equivalent B.N.C. any wiring, can be carried out by the Jetcal Analyzer the periscopic sextant, Kelvin and Hughes Ltd. have types of American manufacture. manufactured by B and H Instrument Co. Inc. of constructed a star simulator which will enable a U.S.A. The instrument tests exhaust gas tempera navigator to use an ordinary periscopic sextant to ture indicators and tachometers, and isolates any take a sight. The simulator has recently been installed Light-weight Flexible Hose errors. at the central training unit of B.O.A.C. A hose which can be used to transport petrol, oil, For checking the exhaust gas temperature system, In using the simulator the navigator first computes pure benzole and other chemicals, and water, and a group of specially designed probes, each containing the altitude and azimuth of the star to be observed and which is light in weight and flexible, has been produced a furnace developing a precisely controlled tempera sets the figures on to the mechanism of the periscopic by the Compoflex Co. Ltd., 26 Grosvenor Gardens, ture up to 900 deg. C, and its own thermocouple, fits sextant. The star should then be visible in the sextant S.W.I. It is a rough-bore hose, called the Feather over the thermocouple in the engine. A potentiometer weight, and is available in a range of bore sizes up to in the analyser measures the temperatures registered 4 inches. The weight per foot ranges from 0·65 lb. for by the neat probes and by the engine system. The the 1½ in. i.d. to2·9 lb. for the 4 in. i.d. hose. thermocouples in the probes are accurate to Bureau of The hose consists of an inner exposed supporting Standards specification and are used to check any wire helix with a fabric liner coated with a special PVC inaccuracies in the aircraft instrument reading. mixture known as Molene, which has a very high Incorporated in the analyser is the Takcal, for resistance to petroleum, oil and general chemicals. For clucking the aircraft tachometer system. It is a use with particular fluids the hose can be fitted with frequency device which is insensitive to fluctuations in special liners of Polysar, Hycar or Butyl instead of voltage and retains its accuracy through all tempera Molene. Over the filler of Polysar is a canvas cover, ture ranges. coated with abrasion-resistant Molene, and another The Jetcal Analyzer can also be used for checking mild steel helix. During its manufacture, the completed exhaust gas temperature thermocouples on the bench hose is steam-cured to bond the materials together and and in the aircraft, for testing associated circuits and form a fully laminated wall. This laminated construc indicators, and thermal switches such as overheat tion allows the gauge of the two wire spirals to be detectors and anti-icing systems. reduced in order to save weight, but ensures that the strength is not impaired. Steam-curing enables the hose to be used at temperatures up to 200 deg. F. Bayonet Cable Connectors The bend radius ranges from 2½ in. for the 1½ in. i.d. Smiths Aircraft Instruments Ltd. now manufacture to 8 in. for the 4 in. i.d. hose; the flexibility has been bayonet type cable connectors for coaxial and single slightly reduced so that the hose will resist over- core cables. Connexion and disconnexion can be done flexing and prevent collapse through overstrain at such with one hand, and the connectors are locked in a way points as fitting junctions. If the hose is accidentally which eliminates vibration. They can be rendered non- crushed it is possible to re-form it by beating. interchangeable by transposing the male and female contacts and using long-throw bayonets, so that in a group of up to three connectors cross connexions External Power Plant cannot be made. Two externally mounted gas turbine units for The following three types of connectors are supplying electrical power to the aircraft will be available: installed on the C-131B electronic test-bed, now cable mounted connectors, to suit cither Uniradio being built by Convair, San Diego, California, for 32 or 70 coaxial cables, 0·15 in. outside diameter, the U.S. Air Force. The engines are Solar T-41 or Uniradio 72 coaxial cable, or Unipren 6. (Con units, and will be mounted under the wing, between nectors for other cables with a slightly different the main engines, in plastic and metal pods attached outside diameter can be supplied as a special to the airframe by pylons and standard bomb shackles. requirement); The pods contain independent fire-detection and extinguishing systems, with provisions for anti-icing panel mounted connectors for mounting on a case in each air intake. or panel where quick release is required. They are 200 Aircraft Engineering
Aircraft Engineering and Aerospace Technology – Emerald Publishing
Published: Jun 1, 1955
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